A flight way of a spherical object like a golf ball, a baseball ball, etc is determined at a moment that physical force is applied to a ball (namely, impact timing by a golf club or a bat). The information used for determining a flight way of a spherical object is formed of a rotation information of a ball (in other words, a rotation speed and a rotation axis), a flight direction, a speed, etc. There is a golf simulation system which is designed to estimate a flight trajectory of a flight spherical object. Most of the golf simulation systems are directed to generating a lattice shaped sensing region in a space through which a trajectory of a golf ball passes, by using a laser, a photodiode, an ultrasonic sensor, etc., whereby to measure a flight direction and speed of a golf ball with the aid of the information such as the position of a shadow of a golf ball or a golf ball measured at a moment that a golf ball passes through a sensing region, and the size of a golf ball. The above conventional golf simulation system is not capable of measuring a rotation information of a golf ball, so a method for estimating a rotation information of a ball by using a motion data (angle, trajectory, etc. of a golf club head) of a golf club is used instead. In this case, there is a limit in measuring the trajectory of an accurate impact of a golf ball. In addition, the conventional golf simulation uses a trigger device generating a light screen by using a photodiode or a laser in order to judge whether or not a ball passes through a certain point for capturing a motion of a ball which flies at a high speed. When a trigger device is used, the trigger device is provided close to a flight way of a golf ball and a golf club at the time of impact, so interferences between a rigger device, a golf ball and a golf club occur.
The US patent publication number 2007-0213139 discloses a system (hereinafter referred to prior art 1) for measuring a trajectory of a golf club and flight parameter of a golf ball with a mark line with the aid of one high speed camera by using two sensor rows. The above system, however, is same a currently commercial screen golf system: The prior art 1 cannot accurately measure the rotation information of a golf ball, and it adapts an expensive high speed camera, thus increasing the whole manufacture cost of the system. Since a sensor is installed at a floor of a player's standing portion or at a certain height from the floor, a player might have psychological burden because a golf game originally gives a player a lot of stress, and a lot of errors occurs due to the malfunction of a sensor.
The Korean patent registration number 10-0871595 discloses a construction (hereinafter referred to prior art 2) which is directed to obtaining a flight information of a golf ball by providing a trigger signal by which initial speed is obtained by picturing the image of a golf ball with at least two mark lines (a circle formed on the surface of a golf ball about a central point of a golf ball in a form of a meridian) by using a high speed line scan camera, and a golf ball is pictured at a regular displacement interval based on two high speed cameras installed at left and right sides of a high speed line scan camera based on the objected initial speed. The above prior art 2 adapts a high speed line scan camera for detecting a golf ball and computing an initial speed, and a high speed camera is adapted to measure a flight parameter of a golf ball, so the entire manufacture cost increases. The prior art 2 does not consider the rotation characteristics of a golf ball. The trigger signal provided for a continuous picturing based on two high speed cameras serves to set about the displacement of a golf ball (in other words, the interval of trigger signals is set so that the golf balls of multiple images taken based on each trigger signal are not overlapped). According to the prior art 2, as shown in FIG. 1, it is impossible to precisely recognize whether or not the golf ball has rotated 30° in clockwise direction or has rotated 30° in counterclockwise direction based on the first taken image and the second taken image.
The US patent publication number 2007-0060410 discloses a system (hereinafter referred to prior art 3) for measuring a flight parameter of a golf ball based on two images taken by continuously picturing a golf ball with dots formed at each apex of a pentagonal shape and center of the same by using one high speed camera or two images taken by continuously picturing with two high speed cameras. The above prior art 3 does not consider the rotation characteristics of a golf ball. A trigger signal serves to set based on the displacement of a golf ball, which signal is provide for a continuous picturing based on one or two high speed cameras (in other words, the interval of trigger signals is set so that the golf balls of multiple images taken based on each trigger signal are not overlapped.) The prior art 3 has a problem that it is impossible to accurately measure whether or not a golf ball has rotates in clockwise direction or in counterclockwise direction, from the first taken image and the second take image.